| Gas permeability of unsaturated fine grained soils was investigated using a new flexible wall biaxial permeability apparatus. The apparatus is capable of measuring gas permeability by three different non-steady state methods. Gas permeability of kaolin clay, silt and cement bentonite samples to air, carbon dioxide and methane were measured.;Effects of liquid saturation and gas type on all three soils were investigated. Effects of compaction moisture content and soil structure on gas permeability of clay and silt samples were studied.;Test results showed that gas permeability depends on liquid saturation, soil structure, gas and soil type. Compaction water content had a large effect on gas permeability of clay samples but had essentially no effect on permeability of silt samples. For a given air void ratio, clay samples compacted wet of optimum had the lowest and silt samples compacted both at dry and wet of optimum had the highest gas permeability. Relationships between air void ratio, air permeability and saturated water permeability are presented for soils with negligible volume change during the drying phase. |
